Briefcase



FIG. 1 is a perspective view of a briefcase;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a top view thereof;

FIG. 5 is a bottom view thereof;

FIG. 6 is a left view thereof; and,

FIG. 7 is a right view thereof.

The broken lines in FIG. 1 are included for the purpose of illustrating a portion of a strap that forms no part of the claimed design. 

CLAIM The ornamental design for a briefcase, as shown and described. 